Furnace conveyer



Sept. 19, 1939. RA. FAHRENWALD I FURNACE GONVEYER 4 Sheets-Sheet 1 Filed Oct. 27/ 1938 Mad.

KQ nw ww Q 4 F. A. FAHRENWALD 2,173,682

FURNACE CONVEYER Filed Oct. 27, 1938 4 Sheets-Sheet 2 (2/24 'j/ifezziacz/al Sept. 19, 1939.

p 19, 1939- F. A. FAHRENWALD 2,173,682

FURNACE G ONVEYE R Filed Oct 2'7, 1938 4 Sheets-Sheet 3 INVENTOR.

l fiazzif .firezzzae/d ATTORNEYS Sept. '19, 1939. F. A. FAHRENWALD 2,173,682

- FURNACE CONVEYER Filed Oct. 27; 1938 4 Sheets-Sheet 4 INVEMOR. 7/ aiz/f QT/ Mrew /c/ ATTORNEYS Patented Sept. 19, 1939 UNITED STATES PATENT OFFICE FURNACE comma Frank A. Fahrenwald, Chicago, Ill. Application October-"27, 1938: Serial No. 237,298 23 Claims. (01.263-28) My invention relates to the heat treatment of materials, and includes among its objects and advantages an improvement in means for conveying material to be treated through a hot chamber or 5 space, particularly with reference to strength,

durability, and freedom from warping, buckling,

and cracking.

In the expansion of the field of service in the heat treating of metal castings, forgings, and the i like, as well as bricks and a wide variety of ceramic products, where the heat treatment usually has a baking action, one of the mainobstacles is the weakness and warping of the instrumentalities used to support and transport the [6- articles through the heated zone in which the treatment takes place.

It has been common heretofore to employ more or less rigid devices, usually of one piece, and not infrequently in the nature of a simple flat tray :0 with or without stiffening walls or flanges, upon which the material is placed while the device is pushed or pulled through, the heated chamber. Such devices are necessarily subjected to the same heat treatment as the articles themselves,

: and the continued repetition of the heat treat- I ment time after time results in rapid deterioration, of which the most annoying feature is the buckling, warping, and even cracking openof the supporting device, due to'the combined action I) of temperature gradients, loss of strength at high temperatures, and the weaving and warping due to track irregularities, This last item of track irregularity is thought of as negligible in conveyers operating at ordinary temperatures, but 5" becomes'highly significant at temperatures where it becomes impossible to employ springs of any sort, because the high temperature would draw the temper of any spring, and where it be comes impracticable to maintain in the track a degree of smoothness that could easily be maintained at ordinary temperatures.

Increasing the weight and over-all rigidity of v the device itself is a step in the wrong direction. 5 Such an increase not only multiplies the heat losses involved in treating the device, as well as it's load, but it also increases the forces caused by temperature difierences, to such an extent'that the heavier and more rigid device destroys itself all the sooner.

In the accompanying drawings: Figure 1 is a side elevation of a support according to the invention; a Figure 2 is a. fragmentary plan view of the 5 same t levice looking down from above;

Figure 3 is a section as on line 3-3 of Figure 1;

Figure 4 is a fragmentary plan view of a modified construction;

Figure 5 is a partial side elevation and Figure 5 6 an end elevation of the structure. of Figure 4;

Figure '7 is a plan view of a simplified construction;

Figure 8 is n end view of the device of Figure 7; and

Figure 9 isa section on line 9-9 of Figure 7. According to the invention, I employ the principle of multiple point contact with the supporting rails, utilizing points spaced widely enough apart to secure stability of the device and its load under the action of gravity. This necessarily implies not less than three points of support, but. stability is greatly increased by the use of four points, and I have selected for illustration an embodiment providing for four points of support.

Referring first to Figures 1 to 3,-the track I0 i has flanges, and the track i2 is flat. Duplicate longitudinal truck members l4 each lie over one of the tracks and each carries spaced wheels [6 mounted in suitable bearings at l8, The bearings at l8 are located withapproximately 60% of the length of the truck members between them,

to secure substantially maximum efliciency in the use of material. Each truckmember is of substantially'hollow box section throughout, and intermediate the bearings" the vertical dimen- 40 sion of the section is increased as clearly indicated at 20 in Figure 1. In general, the section is designed to secure approximately uniform stress in the material when the beam is subiected to approximately uniform loading throughout its length. i

In the embodiment selected for illustration in Figures 1 to 3, the next series ofsupporting members comprises five, spanning members 22, each of I-beam cross section with an. upper flange 24 and a lower flange 26', which lower flange rests under the action of gravity. on the upper surface of the truck member I. As in the case of truck members I, the spanning members 22 are supported at points to secure maximum emciency M member.

between the spanning members 22 are further 2 v intheuseofmateriaLandthelower-flangell of each-spanning member is curved downwardly as best indicated at 28 in Figure 3 to secure approximately uniform stress with uniform loading along the length of the In the embodiment ofFlgures 1 to 3, the spaces 'most, and the rear spanning members with their left ends uppermost, while the cenh'al member still lies level, but no harmful twisting or binding action is developed on either the spanning members or the truck'members l4.

I have provided lost motion connections adequate to prevent complete separation of the parts, but still lea the partsfree to warp as indicated, or to shift materially due to differences in temperature. The upper web of the truck member M where it underlies each bottom flange 26 of the spanning member is provided with curved lugs cast integral with the truck member itself. As clearly indicated-in Figure 1, these lugs extend up and then inwardly over the adjacent edges of the flanges 2 but spaced therefrom. Accordingly, the spanning members may be assembled with the truck member by sliding them endwise to engage the flanges 2G in the... positions indicated in Figure 1. The flanges 26 are widened at 34 to secure additional bearing surface on the truckmembers ll. Torestrain the spanning-member from'permanent displacement parallel to its length, I have provided suitable stop means, in the form ,of rods 36. The rods 38 pass through holes in the webs-3'8 of the spanning members 22, and have their ends bent over at 40. In the narrower portions-of the truck members 14, the lugs 42 engaging the webs of the spanning members are located between the rods 36. Adjacent each wheel IS the truck member is widened to provide the bearings It for the wheel l6; and in the widened portions the lugs 44 are positioned with the rods 36 between the .lugs. But at *every point the clearances between the rods and lugs are ample to allow more than the maximum displacement that could result from difierences in temperature of the different beams, so that the thermal expansion and contraction of the spanning members can not twist or distort the truck members or vice versa. The ends of the truck members ll are provided with sockets at 46 to, receive the end'of fany suitable pulling instrumentality, such as a yoke or har-. ness for coupling the individual truck to another truck or to a pulling device.

Referring now to Figures 4, 5, and 6, I have illustrated a similar truck in which three superposed sets of beams are provided. The truck members in this embodiment are simple channels 48 with downwardly flanges which roll along overthe supporting wheels 5| mounted on stationary pivots at 52. The next set of beams includes spanningm'embers'il which go all the way across the truck and spanning members 56 which extend across under only two of the uppermost longitudinal beams 58. The spanning members 5l ind 5B are I-shaped in cross section,

aivaoes v and where they overlie the truck members It theyhave-laterally projecting lugs at ll. Each lug 8l lies between spaced lugs 02 projecting upward from the truck member 48 and pins pass through aligned holes in lugs 62 and overlie 5 lugs II. The pins 84 are of materially smaller diameter than the holes in which they fltpand' the lugs I are materially narrower than the clearances'between the lugs 62. Also the lugs '2 on opposite sides of a spanning member 54 or Ii are spacedapart materially farther than the width of the flange of the spanning member between them. These clearances permit, relative movement and material warping in all directions between the truck members 48 and the 15 spanning member? 54 and 56. The extreme front spanning membe it and the one next beyond it and 88 are interconnected by bracing webs'lll into a-single piece, the center of which is shaped to provide a socket at I! for receiving a coupling member by means of which the entire truck can be pulled through the furnace. In" other words, the two front spanning members 88 and 68 also constitute the pulling yoke. Totransmit the pull from the yoke back to the truck members 48, 5 each truck member has a flange" at 14 abutting downwardly extending flanges at 16,- which 16 are integral with the web 10. These members 54, 56, 66, and $8, and connected to all 4 of them as best'indicated in Figure fijwiththe same ample clearances between the lower flanges of the beams and the lugs at 82 to prevent any 0 harmful binding between the' second and third sets of beams.

' Referring now to Figures '7, 8, and 9, in which my inventionis shown in a simpler embodiment, the truck members are of channel cross sec- 45 tion with downwardly turned legs, and ride on the rows of supporting wheels .86. At each end the truck member 84 is extended upwardly to form a contact abutment at 88 by means of which, when the conditions of service make such 0 .procedur'e, desirable, a series of such trucks car he pushed throughthe furnace- The spanning members 88 are of I-beam cross section and slide under theJugs 90 as in the embodiment of Figure 1, and the retaining rods 92 are outside the 55 lugs on the truck members'throughout their length. The spanning members 88, taken to gether, define a flexible grid on which the material to be subjected to heat can be supported.

The upper flangesof the spanning members are m turned up at 94 at both ends to facilitate loading the truck without letting part 0f the load work off the'side of the truck as the truck goes,

through the furnace.

It will be noted that in Figures 1, 2, and 3 a the wheels are on the truck structure, but in the other embodiments the wheels are on the track structure.

Without further elaboration, the foregoing will so fully explain my invention that others may, 7 by applying knowledge current at the time of application, readily adapt the same for use under various conditions-of service.

I claim:

1. In a furnace conveyor, in combination: a 7

pair oi tracks; a pair of truck members each supported by said tracks at two spaced points: a plurality of spanning members each supported at two spacedpoints by said truck members; said spanning members collectively defining a gridlike structure adapted to receive and-support an object to be conveyed; connections between said spanning members and said truck members for supporting each spanning member independently of the others; said connections permitting free shitting or rotary displacements between said spanning members and said truck members, largely in excess of any distortion that might be caused by thermal conditions, and nor-, mal loads, and track unevenness, but restraining complete separation of the parts; and roller means carried by said truck members and oper-- ating between said. truck members and said tracks for supporting said truck members and spanning members and load, and permitting the whole to roll along over said tracks; said truck members. extending parallel to said tracks.

2. In a furnace conveyer, in combination: a pair of track; a pair or truck members each supported by said tracks at-two spaced points; a pmrality of spanning members each supported at two spaced points by said truck members; said spanning members collectively defininga gridlike structure adapted to receive and support an object to be conveyed; connections between said spanning members and said truck members for supporting each spanning-member independently of the others; said connections permitting tree shifting or rotary, displacements between said spanning members and said truck. members, largely in excess of any distortion that might be caused by thermal conditions, and normal loads,

and trackunevenness, but restraining complete separation of the parts; and roller meanscar ried by said truck members and operating between said truclrmembers and said tracks-for supporting said truck members and spanning members and load, .and permitting the whole to roll along over said tracks.

3. In a furnace conveyer, in combination: a pair of tracks; a pair of truck members each supported by said tracks at spaced points; a plurality of spanning members each supported at j spaced points by said truck members; j 50 said spanning members collectively defining a gridlilre structure adapted to receive and support an object to be conveyed; connections between said spanning members and said truclr members for supporting each spanning member independently oithe others; said connections permitting free shitting or rotary displacements between said spanning members and said truck members, largely in excess'of any distortion that might be caused by thermal conditions and normal loads,

said truck members for supporting and track unevenness, but restraining complete tort-ion that be caused by thermal'condiin combination; a

largely in excess. of any dis- 3 tions and normal. loads, and track unevenness, but restraining complete separation of the parts: and roller means operating between said truck members and said tracks for supporting said truck members and spanning members and load, and permitting the whole to roll along over said tracks; said truck members extending parallel to by said truck members said truck members'and truck members;

said tracks. I

5. In a furnace conveyer, in combination: a pair of tracks; a pair of truck members; a plurality oi spanning members each supported at two spaced intermediate points by said truck members; said spanning members collectively defining a gridlike structure adapted to receive and "support an object to be conveyed; connections adjacent the points of support between said spanning members and said truck members for supporting each spanning member independently of the others; said connections permitting free shitting or rotary displacements between said spanning members and said truck members, largely in excess of any distortion that might be caused by thermal conditions and normal loads, and track unevenness, butrestraining complete separation of the parts; and roller means carried and operating between said tracks for supporting said truckmembers and spanning members and load, and permitting the whole to roll along over said tracks.

' 6. In a furnace conveyer, in combination: a

pair of tracks; a pair of truck members movably supported on said tracks: a pluralityof spanning members each supported a spaced points by 'said said spanning members collectively defining a gridlike structure adapted to receive and support an object to be conveyed; and connections between said spanning members and said truck members for supporting each spanning member independently oi. the others.

7. In a furnace conveyer, in combination: tracks: parallel. truck members supported by said tracks; parallel spanning, members arranged transversely of said truck members and overlying the'saine; lo'st motion connections between said members and overlying spanning members truck members and said spanning, members permitting free warping of the whole; parallel floor members-arranged transversely of said spanning members and over n the same; and lost motion-connections between said fioor members and said spanning members permitting tree warping of the whole.

58.. In a furnace 'conveyer; in combination: tracks, parallel truck members supported by said tracks; parallel spanning members arranged transversely oi said truck members and overlying the same: lostmotion. connections between said truck members and said spanning members permitting freewarp'ing or the whole; parallel floor members arranged transversely of said spanning connectionsbetween said fioor members and said whole and wheels above said track.

tracks tracks;

-members and overlying the'sam'e: lost motion connections between iloor members and said 5 permitting free warping of the supporting said truck members 9. In a furnace conveyer, in combination: parallel truck members supported by said parallel spanning membersarranged transversely of said truck members and overlying the same; lost motion a '10 said spanning members per- I to dimensions amounting to a minor traction tracks; truck members supported by I spanning members arranged at an angle to saidand said spanning members transversely of said spanning members permitting free warping elfthe whole.. .10. In a furnace conveyer, in combination: said tracks;

truck members and overlying the same; and lost motion connections between said truck members permitting tree warping oi the whole. in combination: truck members supported-by said 12. In a-furnace' conveyer,. tracks; parallel tracks; parallel spanning vmembers arranged truck members and overlying the same; lost motion connections between said truck members and said spanning members permitting'ir'ee warping of the whole; and fingers projecting from'the sides or said spanning mem- 1oz first supports each bers todefine a gridlike structure with thespace between two spanning members partially bridged by said fingers.

' -l3..In a furnace conveyer, in combination:

spaced parallel tracks, spaced contact means engaging said tracks at four points occupying su stantially the corners of a' rectangle; a plurality means andhaving cross sectional dimensions amounting to a minor traction of its length; aplurality of second supports each overlying said first supports and resting on said first supports, said second supports each dimensions mounting to a minor traction of its length; and a pluralityjoi third supports each overlying said second supports and each having cross-sectional dimensions amounting to'a minor fraction of its'length; and stopmeans carried by .in predetermined gaging said tracks at tour I first supports and resting on said ,each of said second each of said second and third supports allowing free movement on tending parallel to said tracks. 7 I a 14. In a furnace conveyer, in combination: spaced parallel tracks. spaced contact means enstantially the corners ofza rectangle; a plurality oi first supports each over said contact means mounting to a minor fraction or its length; a plurality of second supports-each overlying said first supports, having cross-sectional minor fraction of its third supports each said second supports each dimensions amounting to a length; and a plurality of overlying said second supports and having only cross-sectional dimensions amounting to a minor fraction of its length; and stop means carried by 15. In a furnace conveyer, incombination; spaced parallelgtrac gaging tracks'at'iour points occupyi substantially the corners of a rectangle: a plurality length; a plurality oi second sup r each exiending'over more than one of said first supports and resting on said'firs't supports, said second supports each having members peritting free warpbverlying said contact having cross-sectional the underlying. supports with:- limits; said first supports ex-" points occupying sub and having cross sectional dimensions d-third support allowing iree movement on the underlying supportsv within predetermined limits.

, spaced contact meins-en-i cross-sectional amass:

ports allowing free movement on the underlyingsupports within predetermined limits.

16. In a furnace conveyor, in combination: spaced parallel tracks, spaced contact wheels engaging said tracks at four points occupy substantially the corners of arectangle; a plurality of first supports each extending over and carry- I ing two of said wheels and having cross sectional dimensions amounting to a minor traction of its length; a plurality extending over more than one of said first sup ports and resting on and supports each having cross-sectional dimensions amounting to a minor fraction of its length; and stop means carried by said second supports allowing me movement on the underlying supports within predetermined limits. 1'1. In a mrnace conveyer, in combination; spaced parallel tracks; two first supports overlyins said tracks and mensions amounting I V length; spaced contact wheels overlying said tracks and underlying and supporting said first supports; a plurality of second supports .each extending over both said first supports and restin on said first supports said second supports each having cross-sectional dimensions amounting to a minor fraction of its length; and stop-means carried'by each oi! said second supports allowing free movement on the underlying supports within ed limits. I a

18. In a furnace conveyer, in combination: a

'truck chassis made up of members of length greatly exceeding their transverse dimensions; a set of spanning members each oi! length greatly exceeding its transverse dimensions; said set of members overlying said chassis,' and contacting the same at a plurality of points; lost motion connections between all said members preventing complete separation of said spanning members and chassis but permitting tree warping of; the whole; and'track means supporting said 19. In a furnace conveyer, .in combination: a made up ofemembers of length greatly exceedin their transverse dimensions; a set of members each of length greatly exceeding its transverse dimensions; said set of spanning I at a plurality said first supports, said secmembers overlying said chassis, and,

of second supports each having cross sectional 'dito a minor ira'ction of its motion connections between all said members preventing complete separation of said spanning members and chassis but permitting free warping of the whole; and track means supportingsaid chassis; each spanning member having support-- ing contact w'ithsaid chassis 1; two spaced points 20. In a'fgn-nace conveyer, in combination: a pair of tracks; a pair of truck members each supported by said tracks; a plurality of spanning members each supported at spaced points by said truck members; said spanning members collectivelydefining a structure adapted to receive and. connections betweensaid spanning members and said truck members tor S rting I member independently of the others; said connections permitting'iree shitting .or rotary displacements between said largely in excess of any distortion thatmight be .caused by thermal conditions and normal loads, and track unevenness. 'but support an obi ect to be mveyed: a

each spannings anning members andrestraining complete separation of, the parts. 7

21. In a furnace conveyer, in combination:

parallel truck members extending in the direc-' tion of motion; means for supporting and guiding said truck members throughout their movement' through the furnace; a work-carrying spanning member arranged transversely ofsaid truck members and overlying the same; andiost motion connections between said truck' members and said spanning member; said connections permitting freeshifting or rotary displacements between said spanning member and said truck members, largely in excess of any distortion that might be caused by thermal conditions and' normal loads, and track unevenness, but restraining through the furnace; work-carrying spanning members arranged adjacent each other and col-" lectively defined structure adapted to receive and support the work; and lost motion connections between said truck members and said spanning members; said connections permitting free shifting or rotary displacements-between said spanning members and said truck members, largely in arranged to engage said track means and provide both vertical support and lateral guidance for the 'movement ofsaid truck members.

23. In a furnace conveyer, in combination:

v tracks; paralleltrucl; members supported by said tracks; parallel spanning members arranged transversely of said truck members and overlying the same;-1os t motion connections between said truck members and said spanning members per-- mitt'ing free warping of the whole; parallel floor members arranged transversely of said spanning members and overlying the same; and lost motion connections between said floor members and said spanning members permitting free warping of the whole; said truck members having contact surfaces positioned and arranged to engage said track means and provide both vertical support and lateral guidance for the movement of said truck members.

FRANK A. F QHRENWALD. 

